Method for removing rot from potatoes

ABSTRACT

Decayed portions of potatoes are removed by supporting and advancing the potatoes on a series of rollers relative to a plurality of water spray nozzles with rubber fingers being mounted on some of the rollers. The rubber fingers contact the potatoes with sufficient force to penetrate the decayed portions without damaging the peel or other sound portions of the potatoes while water sprays contact the potatoes with sufficient force to remove the penetrated decayed portions while leaving the remaining portions intact.

This application is a continuation of application Ser. No. 149,791,filed May 14, 1980, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process and apparatus for cleaningvegetables prior to further processing. More particularly, it relates toremoving the decayed portions of the exterior of a potato prior to steamor lye peeling of said potato.

2. Description of the Prior Art

Potato processing has become a major industry in the United States and asignificant portion of the nation's potato crop now undergoes some formof preparation before being marketed. Frozen potatoes, potato chips andmashed potato flakes are typical of the products prepared from raw wholepotatoes. For each of these products, it is necessary that the potato bepeeled and blemished portions of the potato flesh be removed prior toprocessing.

The term blemish is used by the U.S. Department of Agriculture ingrading the quality of processed potatoes and includes all defects whichdetract from the appearance of the final processed potato. A greaternumber of blemishes found in a given quantity of processed potatoesleads to a lower quality grade for the associated batch of potatoes.Several types of blemishes occur naturally during the growth ofpotatoes. These include "sunburn" which is a green discolorationresulting from exposure of the potato to sun during growth, "hollowheart" which is a hollow core resulting from overwatering, "scabbing"which is a thickening of the skin resulting from disease of freezing,and insect damage which often results in rot or decay. The terms rot anddecay both denote a breakdown of the tissue of the potato and will beused interchangeably hereinafter.

The majority of blemishes found on harvested potatoes result not fromnatural growth patterns, but rather from bruises which are caused bymechanical impact during harvesting. Initially, such bruises are merelya discoloration located at the peel or skin. With time, however, enzymesreleased by broken cells cause increasingly greater portions of thepotato flesh to rot and turn brown. If the potato peel is breached andbacteria enter, a bacterial rot is caused rather than enzymic rot. Ineither event, large portions of the potato are blemished as a result ofdecay.

Peeling during potato processing is presently accomplished by one of twomethods. Most commonly, the potatoes are treated with a lye solutionwhich raises the skin from the flesh. Alternatively, the potato may besubjected to a blast of pressurized or superheated steam which has thesame effect. After either peeling process, the skin may be washed awayusing a water stream and abrasive rollers, but such scrubbing leaves theblemished areas of the potato intact. Such a skin removal device isdisclosed in U.S. Pat. No. 2,776,690 to Warren.

The method of skin removal described by Warren has little effect onblemishes which extend beneath the potato skin. It is thereforenecessary to manually cut away the blemished portions from the peeledpotato, a tedious and expensive processing step. Another disadvantage ofmanual trimming is that the trimmers often removes good flesh from thepotato since it is difficult to judge the depth of blemish beneath thesurface.

The majority of blemishes which must be removed are rotten or decayedportions of the potato peel and the potato flesh extending inward fromthe peel. It is desirable, therefore, to provide a method and anapparatus to mechanically remove decayed portions from whole potatoeswhile removing little or no undecayed potato flesh.

SUMMARY OF THE INVENTION

The present invention is a method and an apparatus for hydraulicallyremoving the decayed portions of a whole potato prior to the peelingthereof. The method comprises the steps of supporting the potatorelative to a series of water spray nozzles adapted to direct wateragainst all areas of the potato surface, and directing such streams at apredetermined intensity in order to loosen and remove the decayedportions of the potato skin and flesh. The method requires that thewater force applied to the surface of the potato be within a rangestrong enough to remove the rot but not strong enough to disrupt theremaining skin and flesh of the potato.

The apparatus for carrying out the above method comprises a plurality ofrollers forming a path for supporting the potatoes, a means forimpelling said potatoes down said path, nozzle means for directing thewater spray at the potatoes, said potatoes being positioned by therollers to receive spray over their entire surface area, and a means forproviding water to the nozzles within the appropriate pressure range.

The preferred embodiment of the invention includes rollers with anabrasive surface which disrupt the decayed areas of the potato peel inorder to reduce the pressure and quantity of water used.

DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, 1C, 1D, 1E, and 1F show a section of a blemished potato atvarious stages of decay and various stages of treatment by prior artmethods and by the present invention.

FIG. 2 is a graph illustrating the pressure thresholds at which variouscomponents of the potato are eroded.

FIGS. 3A and 3B together comprise a diagrammatic plan view of theapparatus of the present invention.

FIGS. 4A and 4B together comprise a diagrammatic elevation view of theapparatus of the present invention.

FIG. 5A is a section taken along line 5A--5A of FIG. 3A.

FIG. 5B is a section showing the penultimate washing station taken alongline 5B--5B of FIG. 3B.

FIG. 6 is a section illustrating the rake mechanism taken along line6--6 of FIG. 3B.

FIG. 7 is an enlarged plan view showing one of the horizontal spraynozzle assemblies.

FIG. 8 is an enlarged elevation view showing one of the vertical spraynozzle assemblies.

FIG. 9 is an enlarged partial section taken along line 9--9 of FIG. 8.

FIG. 10 is a diagrammatic perspective view of a segment of the rollersupport means and illustrating the water recycle system of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1A illustrates one end of a russet potato P a short time afterharvesting. The potato P has a variety of blemishes resulting both fromnatural growth patterns and from mechanical impacts which occurredduring harvest. The natural blemishes include an eye located at 10 and apatch of thick skin (or scab) located at 12. Bruises resulting fromhandling during harvesting are shown at locations 14, 15 and 16.Initially, such bruises result in a slight discoloration of the flesh asindicated by the shaded areas in FIG. 1A. With prolonged storage,however, decay penetrates deeper into the potato flesh, as illustratedby the larger shaded areas of FIG. 1B. The potato peel becomes dried andbrittle and turns dark.

Since potato processing plants operate for a period ranging from ten totwelve months every year while potato harvesting occurs only during ashort interval in the Fall of each year, it is necessary to store asubstantial portion of the potato crop for a period of many monthsbefore processing. During this period of storage, relatively minorbruises suffered during harvest mature into large areas of rot affectinga significant portion of the potato's volume.

FIG. 1B illustrates the potato of FIG. 1A as it might appear after manymonths of storage. The minor bruises at locations 14 and 16 havepenetrated significantly into the potato flesh. The heavier bruise atlocation 15 has deeply penetrated the end of the potato. The peel at 15has dried and contracted, leaving a brittle surface with small crackstherein. Broken line 17 indicates the initial size of the potato beforeshrinking caused by dehydration. The eye of the potato at 10 and thepatch of thick skin at 12 remain essentially unaltered.

Before being processed into final product, the potato of FIG. 1B must bepeeled and have its blemished areas removed. The next step in the priorart is to peel the potato using conventional lye or steam treatment. Thepotatoes are normally conveyed to the peeler in water which softens therotted areas of the peel which have become brittle, as describedhereinbefore. The results of such peeling are shown in FIG. 1C. Thepeeling step removes the natural blemishes at locations 10 and 12 aswell as the minor bruises at 14 and 16. The decayed portions of the peeland flesh are more resistant to lye and steam peeling than are theintact portions. Thus, in order to remove the minor blemishescompletely, a thick layer of potato flesh from all of the potato surfacemust be removed, as may be seen by reference to the dashed outline 18which indicates the size of the potato prior to peeling. Even with suchexcessive peeling, the major decayed portion at location 15 remains. Toattempt to remove the rot at 15 by steam or lye treatment would resultin near total consumption of the good potato flesh.

After peeling, conventional processing calls for the manual trimming ofthe remainig blemished portion of the potato P. Since trimmers areunable to accurately estimate the depth of the rot, they will usuallycut an additional portion of good potato flesh to insure that all therot is removed. The results of such a cut are shown in FIG. 1E. Weightloss suffered by the potato as a result of such conventional processing,including trimming, often approaches thirty percent. The presentinvention reduces such weight loss, decreases the time that the potatois exposed to steam or lye treatment, and reduces the need for trimmersto manually pare out portions of the potato.

The present invention results from the discovery that decayed or rottedareas of the potato skin and flesh are more susceptible to removal bywater jets having a cross-sectional area and a pressure lying within aparticular range than unblemished portions of the same potato. Bysubjecting the entire surface area of a blemished potato to suchstreams, it is possible to dislodge and remove both the rotted peel anddecayed flesh of the potato without additional mechanical aids. However,as will be explained hereinafter, the combination of such water streamswith certain scrubbing means result in the most efficient removal of rotand is encompassed within the present invention.

As illustrated in FIG. 1D, subjecting the potato P to such streams ofwater removes virtually all the decayed portions of the potato whileleaving the undecayed portions of the potato skin and potato fleshintact. The water jets are able to dislodge the decayed portions of thepotato peel and flesh at locations 14, 15 and 16 until reaching theinterface between the decayed potato flesh and the undecayed potatoflesh shown along hatched lines 21, 22 and 23. The firm flesh below theinterface resists the erosive action of the water jets. Additionally,the water jets are able to remove the patch of thick skin at 12, but theeye at 10 will remain until after the potato is peeled.

The present invention is capable of removing all blemishes on the potatowhich result in rot at the peel and in the flesh extending inwardbeneath the rotted peel. Such blemishes include bruises, scab, manyforms of insect damage, and the like. Blemishes which do not weaken thecell structure, such as "sunburn", or which are internal to the potato,such as "hollow heart", are unaffected by treatment according to thepresent invention.

The removal of decay prior to peeling reduces the loss of good potatoflesh during peeling. Although peeling must still be accomplished byconventional means, the peeling time is reduced since decayed portionswhich require additional treatment are no longer present. The result ofsuch conventional peeling after decay has been removed by the presentinvention is shown in FIG. 1F. The loss of potato is indicated by thearea between the dashed line 25, which represents the volume of thepotato in FIG. 1D, and the solid line which represents the final volumeof the potato after peeling. The amount of potato lost by peeling afterdecay removal (FIG. 1F) is much less than when peeling occurs prior todecay removal (FIG. 1C). In addition, the need to manually trim thepotato, as in FIG. 1E, is reduced or eliminated.

FIG. 2 is a graph illustrating the erosive threshold for variousportions of the russet potato as a function of both water pressure andnozzle diameter. The nozzle diameter relates directly to thecross-sectional area of the water stream, as will be discussedhereinafter. Tests were conducted by directing several water streams atthe surface of the potato. The streams were nondivergent and emanatedfrom a sharp-edged orifice. The upstream pressure and the orificediameters were varied and the results noted. The orientation of thepotato was changed during the test to insure that the entire surfacearea was subjected to the water for a period ranging from one to twoseconds. The potatoes were then examined to determine which surfaceareas had been eroded, said surface areas being classified as undecayedpeel, undecayed flesh, decayed areas which were dried after extendedstorage, and decayed areas which were soaked in water prior totreatment. Four lines are shown on the graph, each line representing thecombination of pressure and nozzle diameter at which each class ofsurface area is first eroded.

Line 31 indicates that the undecayed peel of a potato is resistant towater pressure below approximately 150 psig regardless of the area ofthe water stream (nozzle diameter).

Line 32 indicates that the undecayed flesh of the potato is resistant towater pressure above 50 psig for all nozzle diameters greater thanapproximately 0.07 inches. The slope of line 32 further indicates thatthe resistance to erosion increases with increasing nozzle diameter.

Line 33, on the other hand, indicates that areas of decayed skin andflesh on the russet potato which have dried and become brittle duringstorage are increasingly susceptible to disruption by water pressure asthe nozzle diameter increases. With a nozzle diameter of approximately0.07 inches, a water pressure of approximately 50 psig is required todisrupt the skin. With the nozzle diameter of approximately 0.10 inches,this threshold level of disruption has decreased to approximately 40psig. The reason for this phenomenon is that the decayed peel is removedby forcing water through the cracks and underneath the peel, thuslifting the peel. As the area of the water stream is increased,therefore, the probability that water will breach the peel through acrack increases and it becomes increasingly likely that peel will beremoved.

Line 34 in FIG. 2 represents the threshold of erosion for decayed peeland flesh after soaking in a water bath for approximately 20 minutes.The water pressure required at each nozzle diameter up to approximately0.23 inches is reduced from that required when the potato has not beensoaked.

Normally, the potatoes to be treated will be conveyed in water prior toprocessing by the present invention. From FIG. 2, it will be apparentthat presoaking allows operation at a lower water pressure and thusprovides decreased pumping costs. However, it has been found that notall decayed portions of the potato soften after immersion in water. Forthat reason, it is preferred to operate the water spray of the presentinvention at a pressure above that of the threshold for dried blemishesindicated by line 33.

The shaded area 38 of the graph of FIG. 2 indicates the region ofpreferred operation. The lower boundry of this region is based upon theremoval of dried decay (line 33) with a slight pressure margin to insureremoval. The upper boundary is determined by the threshold at whichundecayed flesh is eroded (line 32). Again, a pressure margin isprovided to insure that no good flesh will be disturbed. The right-handvertical margin is somewhat arbitrary and based on the maximum nozzlediameter consistent with reasonable water consumption.

The significance of the graph of FIG. 2 is that a finite range ofcombinations of water pressure and nozzle diameter exist which willerode the decayed portions of a russet potato while leaving theundecayed portions of the same potato intact. The choice of precisewater pressure and nozzle diameters for a given operation will depend onan optimization of two cost factors. Operation with a small nozzlediameter reduces water consumption, but requires a high water pressureand increased power consumption. Operation with a large nozzle diameterdecreases the power consumption, but also increases water consumption.

The primary object of the apparatus of the present invention is to passthe potatoes being processed through a series of water nozzles withdiameters in the range of from about 0.05 to 0.2 inches operated at apressure in the range from about 25 to 65 psig. A secondary object ofthe apparatus is to provide a means for mechanically disrupting thedecayed portions of the potato prior to treatment with the water spray.Mechanically disrupting the decayed crust on the peel insures thatsufficient cracks are present so that the crust may be removed withminimum water pressure. The precise design of one embodiment of thepresent invention will now be described.

Referring to FIGS. 3A, 3B, 4A and 4B, the apparatus of the presentinvention comprises a frame 40 supporting a plurality of rollers 51-77underlying the potatoes and a plurality of rollers 78-82 for contactwith the ends of the potatoes, a rake assembly 85 adapted to advancepotatoes along the rollers 51-77, horizontal spray nozzle assemblies 90adapted to direct a spray onto the girth of the potatoes, and verticalspray nozzle assemblies 94 adapted to spray the ends of the potatoes.Additionally, a pumping system (FIG. 10) for supplying water to thenozzles, including means for recycling used water to the nozzles, isprovided.

FIGS. 3A and 3B show the layout of the rollers 51-82, the associatedhorizontal spray nozzle assemblies 90, and the vertical spray nozzleassemblies 94. The purpose of the rollers is two-fold. First, therollers position individual potatoes in relation to both the horizontalspray nozzle assemblies 90 and the vertical spray nozzle assemblies 94so that the entire surface area of each potato is subjected to the waterspray. Second, certain of the rollers are intended to mechanicallydisrupt the crusted portions of the potato peel to aid in the erosion ofthe decayed flesh beneath. Such mechanical disruption of the peel allowsthe system to operate very close to the dried decay threshold at line 33of FIG. 2, thus minimizing the power requirements of the apparatus. Withthis in mind, the nature and function of each of the rollers 51-82 willnow be explained.

Potatoes, which may or may not have been previously soaked in water byhydraulic conveying equipment, enter the apparatus through a chute 98(FIGS. 3A and 4A) at one end of the frame 40. The potatoes landgenerally in the valley between rollers 51 and 52 and are alignedaxially by the rotation of said rollers. The surface of the first tworollers is relatively soft with a high coefficient of friction so thatpotatoes will begin rotating when they land in the valley betweenrollers 51 and 52. As seen in FIG. 4A, both rollers 51 and 52 are drivenin a clockwise direction so that a potato lying in the valley betweenwill be rotated in a counterclockwise direction.

Such rotation helps to axially align the potatoes in the valley betweenrollers 51 and 52.

All rollers 51-82 of the present system have diameters approximatelyequal to that of the largest potato to be processed. The speed ofrotation of the rollers is chosen so that a large potato will make atleast one revolution at each "station" between adjacent rollers 51-77driven in the same direction, where said station is the valley betweenthe rollers. The speed of rotation depends, therefore, on the speed atwhich potatoes are advanced along the rollers by the rake assembly 85. Atypical value would be approximately 60 rpm with the rake assembly 85advancing potatoes between stations at a rate of one station eachsecond.

As a potato advances from station 51-52, the axis of the potato isaligned generally with the axes of the rollers. Roller 53 has a raisedsurface of high friction chevrons and is also rotated clockwise asviewed in FIG. 4A. At station 52-53, the potato continues to rotate in acounterclockwise direction, and an additional opportunity is providedfor the potato to become aligned with the rollers.

Roller 54 is a transfer roller having a low friction surface. Byrotating in a counterclockwise direction (FIG. 4A) it damps the spin onthe potato at station 53-54 and serves as a transition to the nextstation 54-55, where the potato is spun in the opposite, clockwise,direction. Additionally, the chevrons on roller 53 act to center thepotato at station 53-54. The centering of the potato at said station, inturn, acts to singulate the potatoes so that only one potato at a timewill be positioned at station 53-54. By positioning the potato at thecenter of the station, there is no room for a second potato. Otherpotatoes will remain in back of station 53-54 until the potato at saidstation has been advanced by the rake assembly 85, as discussedhereinafter.

Rollers 55 and 56 each have a surface comprised of a plurality of rubberfingers or appendages 100 (FIGS. 3A, 4A and 5A) arranged spirally aroundthe roller. The rubber appendages serve two purposes. First, theappendages disrupt the decayed areas on the potato peel prior toapplication of the water spray. The size and flexibility of theappendages is chosen so that the appendages will penetrate the decayedareas on the potato surface which are soft while yielding to the hardareas which are not decayed. Additionally, the spiral arrangement of theappendages 100 acts as a screw conveyor and causes the potato to movetoward roller 78 located adjacent one end of stations 55-56 and 56-57.

Roller 78 (FIGS. 3A and 5A) has a surface comprised of the sameappendages 100 as the appendages 100 that are found on rollers 55 and56. The pattern of the appendages on roller 78, however, need not bespiral. The purpose of roller 78 is to disrupt any decayed peel locatedat one end of the potato surface. Referring to FIG. 5A, the axis 101 ofroller 78 lies in the longitudinal direction of the apparatus and isdisposed above the axis 102 of the transverse roller 55. FIG. 5A furthershows that roller 78 rotates in a clockwise direction (as viewedtherein) which keeps the end of the potato down. Roller 78 is positionedso that the upper half of one end of the potato is contacted by theappendages at a given instant in time. Since the potato is rotated fullyabout its longitudinal axis by rollers 55 and 56, the entire end of thepotato is contacted by roller 78 during the time the potato is atstation 55-56. The same potato end continues to contact roller 78 at thenext station 56-57.

Roller 57 is a transfer roller similar to roller 54 and serves as atransition to roller 58 which is a centering roller similar to roller53. A transition roller is required between rollers 56 and 58 for tworeasons. First, the spiral arrangement of the appendages on roller 56drives the potato in the opposite direction from the chevrons on roller58. If rollers 56 and 58 were adjacent, the forces on the potato betweenwould tend to drive the potato out of transverse alignment. Second,rollers 56 and 58 are driven in opposite directions and roller 57 aidsin reversing the direction of spin on the potato as it advances.

Roller 59 is also a transition roller similar to rollers 54 and 57.Rollers 60 and 61 are similar to rollers 55 and 56 except that thespiral formation of the appendages 100 on said rollers drives thepotatoes in the opposite transverse direction. The longitudinallyaligned roller 79 is associated with rollers 60 and 61 and adapted todisrupt the end of the potato opposite to that disrupted at stations55-56 and 56-57.

The first horizontal spray nozzle assembly 90 and vertical spray nozzleassembly 94 are found at station 60-61. The construction of a horizontalspray nozzle assembly is illustrated in FIG. 7. The assembly 90 consistsof a housing having a plurality of individual nozzle openings 91 on thelower face thereof each having a diameter of approximately 0.10 inches.The nozzles 91 are arranged in such a way that adjacent nozzles overlapin the transverse direction of the assembly 90 (i.e., in the directionof movement of the potatoes therepast) so that there are no gaps in thewater sprays directed at the potato. The width of the assembly housingis approximately one-half inch and the length of the assembly housing isequal to approximately the diameter of the largest potato to beprocessed. As seen in FIGS. 3A and 10, one such assembly 90 is locatedabove station 60-61 at the side thereof adjacent roller 79 where thepotato is positioned by the rollers. The water sprays directed onto thepotatoes from assembly 90 applies a downward force thereby urging thepotatoes against the resilient fingers 100.

At the opposite side of station 60-61, a vertical spray nozzle assembly94 is disposed to direct sprays at the end of the potato which had beentreated previously by roller 78. The construction of such vertical spraynozzle assembly 94 is shown in FIG. 8. The diameter of nozzle openings95 located at the top of the assembly housing is approximately 0.14inches. The length of the assembly housing is equal to approximately0.70 the diameter of the largest potato to be processed. The diameter ofthe remaining (lower) nozzle openings 96 is approximately 0.10 inches.By having the larger water streams strike the uppermost portion of thepotato, the end of the potato is held down against the underlyingrollers 60-62. The vertical spray nozzle assembly 94 is elevated abovethe transverse rollers 60-62 (FIG. 8) so that the spray from saidvertical spray nozzle assembly will strike generally the upper half ofthe potato end. Since the potato completes at least one revolution ateach station, the entire end of the potato will be treated. As with thehorizontal assemblies 90, the nozzle openings 95, 96 overlap slightly inthe direction of movement of the potatoes so that there will be no gapsin the water sprays which stikes a potato.

The next station 61-62 also has vertical and horizontal spray nozzleassemblies 94, 90 associated with it. The layout is the same as for theprevious station except that the horizontal spray nozzle assembly 90 islocated to direct spray toward the half of the potato not sprayed atstation 60-61.

Rollers 62, 63 and 64 are transition, centering and transition rollersrespectively. These rollers act in combination to transfer each potatofrom one side of the apparatus to the other. Rollers 65 and 66 (FIGS. 3Band 4B) are similar to rollers 55 and 56 except that bristles 103 (FIG.4B) have been substituted for the rubber appendages 100. The bristlesare an alternative to the appendages and may be substituted therefor. Itis important that the bristles not be so stiff that they damage the goodpotato flesh. The spiral pattern of the bristles on these rollers 65 and66 drives the potato into another bristled roller 80, similar to rollers78 and 79, as described hereinbefore, with bristles having beensubstituted for the rubber appendages 100. Vertical spray nozzleassemblies 94 and horizontal spray nozzle assemblies 90 are againprovided to remove decay from the potato at stations 65-66 and 66-67.

Rollers 67, 68 and 69 serve to shift the potatoes to the opposite sideof the apparatus in the manner described hereinbefore in connection withrollers 57, 58 and 59.

Rollers 70, 71 and 81, together with the associated horizontal spraynozzle assemblies 90 and vertical spray nozzle assemblies 94 form anadditional cleaning station identical to that formed by rollers 65, 66and 80, except that the opposite end of the potato is subjected to thewater spray from the vertical assemblies 94.

Rollers 72, 73 and 74 together form a final transfer group to shift thepotato position to the opposite side of the apparatus, as describedhereinbefore with reference to rollers 62, 63 and 64.

Rollers 75, 76 and 82, together with the associated horizontal spraynozzle assemblies 90 and vertical spray nozzle assemblies 94, form thefinal cleaning stations prior to exit of the potatoes from theapparatus. Rollers 75 and 76 are identical to one another inconstruction, each having a spiral ridge formed of rubber along theouter surface. The spiral ridge tends to drive the potatoes against theassociated longitudinal roller 82. Having a ridge rather than rubberappendages 100 or brush bristles 103 allows the final cleaning stationto shear off any debris which might be attached to the potatoes. Thelongitudinal roller 82 has a smooth surface since there are no verticalspray nozzle assemblies downstream to remove decay, if any, which wouldbe dislodged by an abrasive surface.

The final transverse roller 77 is a transition roller similar to rollers54, 57, 59 and the like. Roller 77 aids in the smooth discharge ofpotatoes from the apparatus. The potatoes exit onto a separate conveyorsystem (not shown) which transports them to the peel removal section ofthe processing facility.

The rake assembly 85, illustrated in FIGS. 3A, 3B and 6, is necessary toadvance potatoes along the rollers 51-77. The rake assembly comprises aplurality of individual combs 106 supported on a pair of endless chains105. The endless chains 105 are supported above the train of rollers bypairs of sprockets 107. Each of the rollers 51-77 are sectionized, asshown in FIG. 6, in order to allow the tines 108 projecting from thecombs to penetrate the periphery of the rollers. A minimum number oftines 108 must be provided so that the space between adjacent tines 108is less than the minimum expected diameter of the potatoes beingprocessed. The spacing between combs 106 along the endless chains shouldbe equal to a distance of six times the diameter of the rollers. Thecombs 106 first penetrate the rollers at station 53-54 and continuealong the remainder of the rollers and past the final roller 77.

The speed at which the endless chains 105 are driven determines thespeed at which potatoes advance down the train of rollers 51-77. Thespeed will depend on the amount of decay found in the potatoes beingprocessed and will be the maximum possible consistent with a high degreeof decay removal.

While the system speed may vary depending on the condition of thepotatoes being treated, the speed at which the rollers are rotateddepends directly on the speed at which the rake assembly 85 is beingdriven. It is essential that each potato remain at each station for theinterval of time necessary for the potato to complete one fullrevolution. On the other hand, it is important that the rollers bedriven at the minimum speed consistent with the aforementionedobjective. Since all rollers are sized to have a diameter equal to thediameter of the largest potato processed, it is necessary to drive therollers so that the tangential surface velocity of the roller is equalto the linear velocity of the combs of the rake assembly 85. Such arelation will insure the proper operation of the apparatus of thepresent invention.

FIG. 9 illustrates a single nozzle opening 96 in the vertical spraynozzle assembly 94. The nozzle 96 is a sharp-edged orifice which resultsin a substantially nondivergent flow pattern with a steam diameterslightly smaller than the diameter of the orifice. The nozzle openingillustrated is typical of all nozzle openings of the preferredembodiment except that nozzle openings 95 have a larger diameter. Thenozzle openings used in the tests which resulted in the graph of FIG. 2were also sharp-edged orifices.

FIG. 10 illustrates the water recycling system of the present invention.The frame 40 supports a screen 110 which projects downward from theframe at approximately a 45° angle. The screen 110 extends beneath therollers 51-77 and is adapted to collect water and debris as it fallsdownward between said rollers. A baffle 112 extending beneath therollers 51-77 from the opposite side of the frame 40 is provided to helpdirect water and debris to the screen.

The screen 110, with openings of approximately 0.02 inches, is adaptedto remove the larger particulates from the water so that the water maybe recycled by a pump 114. The separated particulates are washed overthe screen and collected by conventional means not shown. The waterpassing through the screen is collected in a trough 116 where it passesto a recycle manifold 118.

A sufficient amount of water is purged from the recycle manifold 118 tomaintain a predetermined concentration of particulates consistent withproper spraying through the nozzles. Make-up water is added to replacethe water bled from the system. The water is then fed by pump 114 to thenozzle manifold 120 where it is directed to the individual nozzleassemblies 90, 94. Vertical spray nozzle assemblies 94 are mounted onshort risers 122 extending upward from the nozzle manifold 120 andconnected thereto. The horizontal spray nozzle assemblies 90 are mountedat the end of L-shaped pipe sections 124, 126 adapted to support thenozzle assemblies at the appropriate locations and carry water to saidassemblies. Note that the vertical assemblies 94 and horizontalassemblies 90 at each station are longitudinally offset so that thesprays therefrom will not interfere with each other.

Endless chains 130 and 132 are provided on either side of the frame 40in order to rotate the rollers in the appropriate direction. Chai 130 isdriven in a counterclockwise direction (as viewed in FIG. 10) and isadapted to drive all rollers which are required to be rotated in thatdirection. For example, rollers 59, 60 and 61, all of which rotate inthe counterclockwise direction, are all provided with sprockets 135which engage chain 130. On the opposite side of the frame, rollers 61and 62 are provided with sprockets (not shown) to engage chain 132,which chain is driven in the opposite direction to chain 130. Means fordriving the chains 130 and 132 are wholly conventional and are notillustrated.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

What is claimed is:
 1. A method for removing decayed portions from theexterior of an untreated unpeeled potato with apparatus which includespotato supporting means and a plurality of rubber fingers, consistingessentially of the steps of:supporting said potato relative to aplurality of water nozzles; contacting substantially all surfaces of thepotato with rubber fingers with sufficient force to crack the skinencompassing the decayed portions and to penetrate the decayed areas ofthe potato surface without damaging the peel or flesh of sound portionsof the potato; and directing a plurality of water streams through thenozzles so that the water strikes substantially the entire surface ofsaid potato for urging the potato against said rubber fingers withsufficient force to cause the fingers to penetrate the decayed portionsand for disrupting and removing decayed portions from the potato withoutdamaging the peel or flesh of sound portions of the potato, said decayedportions including decayed portions of the skin and decayed interiorportions of the potato extending inwardly from the skin, while leavingthe remaining portion of the potato surface intact.
 2. A method as inclaim 1, and additionally comprising the step of contacting the surfaceof the potato and penetrating the decayed portions prior to directingsaid water streams thereat for reducing the amount of water required toremove said decayed portions from the potato.
 3. A method according toclaim 1 or 2 and additionally comprising the step of rotating the potatowhile being contacted by said rubber fingers and said water streams forassuring that one or more fingers and one or more water streams engagesubstantially the entire exterior surface of the potato.
 4. A methodaccording to claim 2 wherein the diameter of said water streams ispreferably within the range of about 0.05 to 0.20 inches and whereinsaid water pressure preferably lies within the range of about 25 to 65psig.
 5. A method according to claim 1 or 2 wherein the potato isrotated at least one revolution when being subjected to said fingers andwater streams.
 6. A method for removing the decayed peel and decayedflesh portions from the skin and underlying sound portions of a potatowith apparatus including potato supporting means and a plurality ofrubber fingers consisting essentially of: the steps of supporting thepotato, contacting substantially all portions of the surface of thepotato with the fingers with sufficient force to crack the skinencompassing the decayed portions and to penetrate the decayed portionsof the potato surface without damaging the peel or flesh of soundportions of the potato, and directing streams of liquid againstsubstantially all portions of the surface of the potato at a sufficientpressure for washing the potato and for forcing liquid through cracksand underneath the decayed peel for lifting the decayed peel andremoving the decayed flesh while removing a minimum of sound peel andsound flesh of the potato.
 7. A method according to claim 6 andadditionally comprising the step of establishing relative rotationbetween the potato and said rubber fingers while the potato is beingcontacted by said fingers.
 8. A method for removing decayed portionsfrom the sound portions of a potato with apparatus including potatosupporting means and a plurality of rubber fingers; consistingessentially of the steps of supporting the potato, contactingsubstantially all portions of the surface of the potato with the rubberfingers with sufficient force for causing the rubber fingers topenetrate the decayed portions without damaging the flesh of soundportions of the potato, urging the potato against said rubber fingerswith sufficient force to cause the fingers to penetrate the decayedportions, and directing streams of liquid having a diameter of betweenabout 0.05 to 0.2 inches against substantially all portions of thesurface of the potato at a pressure within the range of about 25 to 65psig for washing the potato and removing the remaining decayed fleshwhile removing a minimum of sound flesh from the potato.
 9. A method forremoving decayed portions from the exterior of a potato with the aid ofa plurality of rubber appendages, consisting essentially of the stepsof:supporting said potato relative to a plurality of water nozzles;engaging the exterior of the potato with the rubber appendages withsufficient force to disrupt the decayed areas of the potato, the sizeand flexibility of the appendages being chosen so that the appendageswill penetrate the decayed areas of the potato surface which are softwhile yielding to the hard areas which are not decayed; and directing aplurality of water streams through said nozzles so that water strikessubstantially the entire surface of said potato, said water streamshaving sufficient force to disrupt and remove said pentrated decayedportions from the potato, said decayed portions including interiorportions of the potato extending inwardly from the surface, whileleaving the remaining portions of the potato surface intact.
 10. Amethod according to claim 6 wherein the rubber fingers are mounted on aplurality of driven rollers including two pairs of potato supportingrollers and end rollers positioned adjacent opposite ends of associatedpairs of said potato supporting rollers; and additionally comprising thesteps of spirally orienting the fingers on one pair of potato supportingrollers for driving the potato in one direction for engaging one end ofthe potato against the fingers of one of said end rollers, and orientingthe fingers on another pair of potato supporting rollers for driving thepotato in the opposite direction for engaging the other end of thepotato against the fingers of the other of said end rollers, said stepof directing streams of liquid against the potato including directingstreams of water against one end portion of the potato when the oppositeend portion of the potato is contacted by said rubber fingers of one endroller.
 11. A method according to claim 8 wherein the rubber fingers aremounted on a plurality of driven rollers including two pairs of potatosupporting rollers and end rollers positioned adjacent opposite ends ofassociated pairs of said potato supporting rollers; and additionallycomprising the steps of spirally orienting the fingers on one pair ofpotato supporting rollers for driving the potato in one direction forengaging one end of the potato against the fingers of one of said endrollers, and orienting the fingers on another pair of potato supportingrollers for driving the potato in the opposite direction for engagingthe other end of the potato against the fingers of the other of said endrollers, said step of directing streams of liquid against the potatoincluding directing streams of liquid against one end portion of thepotato when the opposite end portion of the potato is contacted by saidrubber fingers of one end roller.
 12. A method according to claim 9wherein the rubber fingers are mounted on a plurality of driven rollersincluding two pairs of potato supporting rollers and end rollerspositioned adjacent opposite ends of associated pairs of said potatosupporting rollers; and additionally comprising the steps of spirallyorienting the fingers on one pair of potato supporting rollers fordriving the potato in one direction for engaging one end of the potatoagainst the fingers of one of said end rollers, and orienting thefingers on another pair of potato supporting rollers for driving thepotato in the opposite direction for engaging the other end of thepotato against the fingers of the other of said end rollers, said stepof directing streams of water against the potato including directingstreams of water against one end portion of the potato when the oppositeend portion of the potato is contacted by said rubber fingers of one endroller.